Clean up some GN toolchain args, especially NaCl.

build/toolchain/gcc_toolchain.gni

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/toolchain/toolchain.gni")
 
 # This value will be inherited in the toolchain below.
 concurrent_links = exec_script("get_concurrent_links.py", [], "value")
 
 # This template defines a toolchain for something that works like gcc
 # (including clang).
 #
 # It requires the following variables specifying the executables to run:
 #  - cc
 #  - cxx
 #  - ar
 #  - ld
 # and the following which is used in the toolchain_args
 #  - toolchain_cpu  (What "current_cpu" should be set to when invoking a
 #                    build using this toolchain.)
 #  - toolchain_os  (What "current_os" should be set to when invoking a
 #                   build using this toolchain.)
 #
-# Optional parameters:
+# Optional parameters that control the tools:
+#
 #  - libs_section_prefix
 #  - libs_section_postfix
 #      The contents of these strings, if specified, will be placed around
 #      the libs section of the linker line. It allows one to inject libraries
 #      at the beginning and end for all targets in a toolchain.
 #  - solink_libs_section_prefix
 #  - solink_libs_section_postfix
 #      Same as libs_section_{pre,post}fix except used for solink instead of link.
 #  - link_outputs
 #      The content of this array, if specified, will be added to the list of
 #      outputs from the link command. This can be useful in conjunction with
 #      the post_link parameter.
 #  - post_link
 #      The content of this string, if specified, will be run as a separate
 #      command following the the link command.
 #  - deps
 #      Just forwarded to the toolchain definition.
 #  - executable_extension
 #      If this string is specified it will be used for the file extension
 #      for an executable, rather than using no extension; targets will
 #      still be able to override the extension using the output_extension
 #      variable.
-#  - is_clang
-#      Whether to use clang instead of gcc.
-#  - is_component_build
-#      Whether to forcibly enable or disable component builds for this
-#      toolchain; if not specified, the toolchain will inherit the
-#      default setting.
 #  - rebuild_define
 #      The contents of this string, if specified, will be passed as a #define
 #      to the toolchain. It can be used to force recompiles whenever a
 #      toolchain is updated.
 #  - shlib_extension
 #      If this string is specified it will be used for the file extension
 #      for a shared library, rather than default value specified in
 #      toolchain.gni
 #  - strip
 #      Location of the strip executable. When specified, strip will be run on
 #      all shared libraries and executables as they are built. The pre-stripped
 #      artifacts will be put in lib.stripped/ and exe.stripped/.
+#
+# Optional build argument contols.
+#
+#  - clear_sanitizers
+#      When set to true, is_asan, is_msan, etc.will all be set to false. Often
+#      secondary toolchains do not want to run with sanitizers.
+#  - is_clang
+#      Whether to use clang instead of gcc.
+#  - is_component_build
+#      Whether to forcibly enable or disable component builds for this
+#      toolchain; if not specified, the toolchain will inherit the
+#      default setting.
 template("gcc_toolchain") {
   toolchain(target_name) {
     assert(defined(invoker.cc), "gcc_toolchain() must specify a \"cc\" value")
     assert(defined(invoker.cxx), "gcc_toolchain() must specify a \"cxx\" value")
     assert(defined(invoker.ar), "gcc_toolchain() must specify a \"ar\" value")
     assert(defined(invoker.ld), "gcc_toolchain() must specify a \"ld\" value")
     assert(defined(invoker.toolchain_cpu),
            "gcc_toolchain() must specify a \"toolchain_cpu\"")
     assert(defined(invoker.toolchain_os),
            "gcc_toolchain() must specify a \"toolchain_os\"")
@@ skipping 226 matching lines @@
     # When invoking this toolchain not as the default one, these args will be
     # passed to the build. They are ignored when this is the default toolchain.
     toolchain_args() {
       current_cpu = invoker.toolchain_cpu
       current_os = invoker.toolchain_os
 
       # These values need to be passed through unchanged.
       target_os = target_os
       target_cpu = target_cpu
 
-      if (defined(invoker.is_clang)) {
-        is_clang = invoker.is_clang
-      }
-      if (defined(invoker.is_component_build)) {
-        is_component_build = invoker.is_component_build
+      forward_variables_from(invoker,
+                             [
+                               "is_clang",
+                               "is_component_build",
+                             ])
+
+      if (defined(invoker.clear_sanitizers) && invoker.clear_sanitizers) {
+        is_asan = false
+        is_cfi = false
+        is_lsan = false
+        is_msan = false
+        is_syzyasan = false
+        is_tsan = false
       }
     }
 
-    if (defined(invoker.deps)) {
-      deps = invoker.deps
-    }
+    forward_variables_from(invoker, [ "deps" ])
   }
 }